Terms of use for slideshow photos with Google Maps plugin

I am using the Google Maps plugin on a site for a conference (attendees are charged to attend). I am using Google Maps plugin to provide directions, but would also like to show the slideshow (so people can see something about the area). I want to make sure this is legal/allowable - I can't find anything about terms of use for using those photos. I'm guessing most of them are uploaded to Google Images or something, but are there attribution/payment requirements to keep from copyright violation?